Pollution: Rapid growth, lax enforcement of environmental laws and its desert location give the metropolis some of the dirtiest air in the West.

LAS VEGAS — Any given day, the view across this desert valley--the fastest growing metropolitan area in the nation--shows a carpet of homes stretching to the foothills, sprawling beneath not blue skies but a yellowish-tan haze.

Distracted by the demands of an expanding population--new roads, new water lines and new schools--government officials here have failed to keep up with one of the most toxic side effects of growth: air pollution. As a result, Las Vegas--which outsiders may associate with images of sparkling neon piercing a crisp desert sky--today has some of the worst air quality in the Western United States.

A decade of unfettered growth, with scant attention paid to air pollution, has created a public health and bureaucratic mess that may take years to reverse, experts say.

"Our elected officials don't take this seriously, and the air quality officials have been either inept or corrupt or both," said Peggy Pierce, a leader of the Southern Nevada Sierra Club. "I'd prefer the nickname of 'Sin City' to 'Smog City,' but that's what we've become."

Confronted with mounting criticism, the head of the local air quality agency resigned in August, leaving his replacement hobbled with low staff morale and government reports condemning officials for lax enforcement of clean air laws.

New Director Christine Robinson, 32, has launched several tough new clean air initiatives. Her marching orders are clear: Bring order to the anti-smog program serving Las Vegas and surrounding Clark County.

"It's been obvious to everyone we need to take our air quality problems more seriously," she said.

But the effort is so belated that air quality improvements, federally mandated for more than a decade, are still years away. Despite three attempts during the 1990s, local officials have yet to produce a strategy to clean up dust and soot that is deemed credible by the U.S. Environmental Protection Agency, and are expected to miss this year's federal deadline to clean up hazy skies.

Geography and Climate Conspire

Las Vegas sits on the edge of the Mojave Desert in a 500-square-mile valley ringed by the ridges of the Southwest's Great Basin. Summers are hot and dry, winds roar in spring and winters are cold and stagnant. Mix in 1.4 million people and it's a recipe for dirty air.

The biggest mess is caused by wind-blown dust. It's a major component of so-called particulate pollution, which has been linked in several studies to respiratory diseases, including lung cancer, bronchitis and premature death.

Some of the dust is of natural origin. Though desert topsoil usually develops a wind-resistant crust, as much as 31,000 tons of dust comes from the open desert, in part because off-road vehicles break the natural surface seal.

But a bigger contributor is the feverish pace of construction, which spews an estimated 53,000 tons of microscopic grit into the air over Las Vegas annually.

Exasperated EPA officials have moved to take control of Clark County's air program--as the agency did in the Phoenix area in 1998, after years of foot-dragging by officials there.

Last month the EPA started a countdown that could lead to sanctions against Clark County, beginning next year. The region stands to lose millions of dollars in highway funds and may face growth restrictions.

"It's a terrible mess," said David P. Howekamp, who managed EPA's air programs in the Southwest for 18 years until recently. "Las Vegas is a wild place. . . . It is local politics at its worst."

The situation isn't lost on the state Legislature, which commissioned independent analysts to assess Clark County's smog-control program.

"The county has been dragging its feet something terrible," said state Sen. Dina Titus (D-Las Vegas), a longtime critic of the region's pell-mell growth. "The County Commission is very tied to developers and growth, and hasn't wanted to crack down, and that's what's gotten us to this stage."

In September, consultants to the state concluded that the county's anti-smog program is understaffed and underfunded, poorly enforced, and disorganized and lacks a clear idea about how much pollution is emitted and exactly where it all comes from--the very foundation of effective clean air efforts in California and other Western cities.

Just one inspector in the Clark County Health District has been assigned to police 1,000 manufacturers and other businesses under permit, according to the state-sponsored audit by Environ International Corp.

EPA audits in 1992 and 1996 found that local regulators allow some new polluters to escape stringent controls required by the federal Clean Air Act, either by writing unenforceable guidelines or by not requiring the best available emission control devices.

EPA Begins to Punish Polluters

EPA officials say they've been slow to respond to the situation in Las Vegas because they were preoccupied with more pressing air pollution problems in California and Arizona.